Ruby Dee, one of the most enduring actresses of theater and film, whose public profile and activist passions made her, along with her husband, Ossie Davis, a leading advocate for civil rights both in show business and in the wider world, died on June 11, 2014 at her home in New Rochelle, N.Y. She was 91.

Her daughter Nora Davis Day confirmed the death.

A diminutive beauty with a sense of persistent social distress and a restless, probing intelligence, Ms. Dee began her performing career in the 1940s, and it continued well into the 21st century. She was always a critical favorite, though not often cast as a leading lady.

Her most successful central role was Off Broadway, in the 1970 Athol Fugard drama, “Boesman and Lena,” about a pair of nomadic mixed-race South Africans, for which she received overwhelming praise. Clive Barnes wrote in The New York Times, “Ruby Dee as Lena is giving one of the finest performances I have ever seen.”

Her most famous performance came more than a decade earlier, in 1959, in a supporting role in “A Raisin in the Sun,” Lorraine Hansberry’s landmark drama about the quotidian struggle of a black family in Chicago at the dawn of the civil rights movement. Ms. Dee played Ruth Younger, the wife of the main character, Walter Lee Younger, played by Sidney Poitier, and the daughter-in-law of the leading female character, the family matriarch, Lena (Claudia McNeil). Photo Sidney Poitier and Ruby Dee in “A Raisin in the Sun,” which opened on Broadway in 1959. Credit via Photofest